The North American strain of gypsy moths (species Lymantria dispar), or its ancestral European strain, has been known in North America since the later 1800's, and by 1889 serious damage from this strain of gypsy moth was being-reported in wooded areas by researchers. Gypsy moths are considered devastating insect pests in their larva stage when they are leaf-eating caterpillars. These caterpillars can ravage entire forests. As adults, the gypsy moths do not have working mouth parts, so they cannot feed, and they live only a few days or weeks. The North American gypsy moths have wings, but cannot use them to fly. Instead they catch a breeze and glide on it. Thus the spread of this strain of gypsy moth is not considered rapid, and researchers are able to wipe out centers of infestation when detected. Thus to an extent the North American strain of gypsy moth has been suppressed, but since it is found in forests in New England, the Northeast, and the Mid-Atlantic states, and has also been detected as far west as the Pacific Northwest, over the many decades of efforts it clearly has not been eradicated.
In the early 1980's the Asian strain of gypsy moth was introduced to North America, apparently being transported aboard foreign trade vessels that docked in Seattle, in Portland, Oreg., and in Vancouver, British Columbia. The caterpillars of this strain have been observed using tiny threads of silk to become airborne, permitting them to be carried off like kites, and thus the caterpillars themselves spread to acres of forests inland. The capability of this Asian strain to spread is believed intensified by the fact that the females have working wings. The females fly. Their spread is more rapid than the North American strain and hence wiping out a center of infestation is a much more difficult task. It is possible that the Asian strain has spread throughout most of the North American continent.
The Asian strain of gypsy moth is also more threatening than the North American strain because of the caterpillars' eating habits. They are more voracious eaters and they feast on more varieties of trees than the North American gypsy moth caterpillars. While preferring oak, they will feed on almost any tree or shrub. Known hosts include alder, apple, basswood, birch, box elder, hawthorn, hazelnut, mountain ash, poplar, willow and witch hazel trees, rose bushes, and sumac plants.
The introduction of the Asian strain of gypsy moth is believed to be adding to the destruction of thousands of trees and is leading to the increased use of insect-control agents. The watersheds in Washington, Oregon and British Columbia are in jeopardy of damage. The national forests of the United States are believed in jeopardy. North American agriculture may be threatened, and is already burdened with the costs of suppressing these strains of gypsy moths.
The term "insect-control agent" is defined as any chemical that can alter or destroy the normal life cycle of the insect in question. Chemicals which can fall into this category are insecticides, miticides, phermones, and the like.
One weapon being used to combat the gypsy moth problem is displarlure, a sex pheromone, which is known to disrupt the procreation cycle of at least the North American strain of gypsy moth. The pheromone has been used to lure the males to insecticides or to physical traps. Such traps, however, provide too limited an area of protection when the plant life to be protected extends over vast areas, which at times can be millions of acres.
For large scale protection, one currently used method is to incorporate such pheromone as beads into a composition that can be sprayed over acres of foliage and there become attached to leaves and tree limbs and stems and the like, so that a male gypsy moth, now being attracted to the surrounding multiple sources of the pheromone, becomes distracted to the point of procreation failure. The males cannot located females in such environment.
Such large scale protection requires the pheromone beads to be well distributed throughout the canopy of a forest or other foliage area to be protected. Such distribution is best achieved by spraying a pheromone bead-containing composition from above, and therefore from an airplane. The pheromone bead-containing composition must have a viscosity that is sufficiently low for spraying. The pheromone bead-containing composition must include an adhesive or sticker (discussed in more detail below) which adheres the pheromone beads to the foliage that comes into contact with the composition. The pheromone bead-containing composition, as sprayed, generally contains a high level of water, and thus the various components of such composition are typically diluted with water prior to spraying to achieve a sprayable mixture. Such dilution, when the composition is sprayed from an airplane, is routinely made in-flight, using a simple recirculating pump to admix the various components prior to spraying.
An adhesive or sticker formulation, to be suitable for use for large scale spraying from an airplane, thus must be readily dispersible with water, so as to be thoroughly admixed with the water and the pheromone beads using a simple recirculating pump. The adhesive or sticker therefore must not only have the desired adhesive properties, which are discussed in more detail below, but also have the relatively low viscosity required for rapid water dispersibility using only simple admixing means such as a recirculating pump.
To be suitable for spraying from an airplane, the pheromone bead-containing composition must predictably fall to the target area, and not drift with the wind. Thus the droplets formed upon spraying must be of sufficient size. To provide suitably sized droplets generally drift control agents are used. Drift control agents are compositions that promote coalescence of fine droplets into larger droplets or strands of droplets, for instance fine mists of from about 200 to about 800 microliters or strands of several inches long, which size range is generally considered suitable to minimize the drifting of compositions when sprayed. A drift control agent for use in pheromone bead-containing compositions, however, must also be readily water dispersible, and must not interfere with the performance of the adhesive or sticker. A typical drift control agent will interfere with the performance of a sticker and will be difficult to disperse in water using a simple recirculating pump or the like without the inclusion of a water miscible solvent of some type in the drift control formulation. Such type of solvents, however, generally will add flash point characteristics to the formulation which is not desirable.
As to the adhesive or sticker performance, as discussed more filly below, the adhesive should provide not merely good bonding between the pheromone beads and the foliage, but also bonding that is resistant to weather conditions, particularly rain and wind.
It is an object of the present invention to provide an adhesive formulation that can be used with pheromone beads, dusts, flakes, powder and the like solid forms of this distracter, and other pesticides for which there are similar use techniques and performance goals. It is an object of the present invention to provide such adhesive formulation that provides excellent water insolubility characteristics to the deposit film. It is an object of the present invention to provide such an adhesive formulation that provides excellent retention of the active components, such as the pheromone beads, on the foliage. It is an object of the present invention to provide such an adhesive formulation that is readily dispersible in water without any high energy admixing and thus can be readily admixed with simple equipment such as a recirculating pump. It is an object of the present invention to provide such an adhesive formulation that provides a pheromone bead-containing composition, or the like, that can be easily sprayed from an airplane, not only because of its water dispersibility, but also because of its drift properties. It is an object of the present invention to provide such an adhesive formulation without the use of any flash point creating solvents. It is also an object of the present invention to provide pheromone bead-containing compositions including such an adhesive formulation, and a method for using such pheromone bead-containing formulation. These and other objections of the present invention are described in more detail below.